A command-line tool written in Python for creating and maintaining SKOS-vocabularies with Excel and GitHub. The voc4cat tool can be run locally but is also well suited for integration in CI-pipelines. It is for example used to maintain the SKOS vocabulary for catalysis voc4cat on GitHub. Several features are included. Conversion between SKOS/turtle representation and Excel/xlsx. The conversion is supported in both directions. Checking of vocabularies. This includes formal validation with SHACL-profiles but also additional checks useful for vocabulary maintenance. Transforming of vocabularies, which includes switching between different Excel representations or between different RDF representations. Documentation generation for publishing the vocabulary for example on GitHub pages.